Friction stir welding apparatus and friction stir welding method

Abstract

Provided are a friction stir welding apparatus and a friction stir welding method that achieve highly accurate and highly reliable joining while minimizing an effect of bending of a pressing force receiving portion (carrying table) as a result of a press by a joining tool unit. The friction stir welding apparatus joins joining target members by friction stir welding. The friction stir welding apparatus is characterized by including: an apparatus main body; a control device that controls an operation of the friction stir welding apparatus; a C-shaped frame connected to the apparatus main body via a first vertical movement drive mechanism unit; a holder unit connected to one end of the C-shaped frame via a second vertical movement drive mechanism unit; and a joining tool held by the holder unit. The C-shaped frame includes a held portion connected to the apparatus main body via the first vertical movement drive mechanism unit, a holder unit holding portion connected to the holder unit via the second vertical movement drive mechanism unit, and a pressing force receiving portion connected to the other end of the C-shaped frame and receiving a pressing force from the joining tool. The control device includes a first joining mode that performs friction stir welding based on a joining command signal that determines a joining condition of the joining tool, and a first holding position determining signal that determines a first holding position of the first vertical movement drive mechanism unit, and a second joining mode that performs friction stir welding based on the joining command signal and a second holding position determining signal obtained by correcting the first holding position determining signal such that a depth or a range of a joined portion becomes constant in accordance with a state of the pressing force receiving portion. The first joining mode and the second joining mode are included in one joining pass from insertion of the joining tool into the joining target members to extraction of the joining target members.

The invention claimed is: 
     
       1. A friction stir welding apparatus that joins joining target members by friction stir welding, the friction stir welding apparatus comprising:
 an apparatus main body; 
 a control device that controls an operation of the friction stir welding apparatus; 
 a C-shaped frame connected to the apparatus main body via a first vertical movement drive mechanism unit; 
 a holder unit connected to one end of the C-shaped frame via a second vertical movement drive mechanism unit; and 
 a joining tool held by the holder unit, 
 wherein the C-shaped frame includes 
 a held portion connected to the apparatus main body via the first vertical movement drive mechanism unit, 
 a holder unit holding portion connected to the holder unit via the second vertical movement drive mechanism unit, and 
 a pressing force receiving portion connected to the other end of the C-shaped frame and receiving a pressing force from the joining tool, 
 the control device includes 
 a first joining mode that performs friction stir welding based on a joining command signal that determines a joining condition of the joining tool, and a first holding position determining signal that determines a first holding position of the first vertical movement drive mechanism unit, and 
 a second joining mode that performs friction stir welding based on the joining command signal and a second holding position determining signal obtained by correcting the first holding position determining signal such that a depth or a range of a joined portion becomes constant in accordance with a state of the pressing force receiving portion, and 
 the first joining mode and the second joining mode are included in one joining pass from insertion of the joining tool into the joining target members to extraction of the joining tool. 
 
     
     
       2. The friction stir welding apparatus according to  claim 1 , wherein the control device determines the joining condition of the joining tool, and the holding position of the C-shaped frame by the first vertical movement drive mechanism unit in either the first joining mode and the second joining mode. 
     
     
       3. The friction stir welding apparatus according to  claim 2 , wherein the control device starts friction stir welding for the joining target members in the first joining mode, and switches to the second joining mode after an elapse of a predetermined time. 
     
     
       4. The friction stir welding apparatus according to  claim 1 , wherein the control device includes a storage unit that stores the joining command signal, the first holding position determining signal, and the second holding position determining signal. 
     
     
       5. The friction stir welding apparatus according to  claim 4 , wherein the control device causes the storage unit to store beforehand the holding position of the C-shaped frame determined in accordance with an elapsed time after a start of friction stir welding, and determines the second holding position determining signal based on the stored holding position. 
     
     
       6. The friction stir welding apparatus according to  claim 5 , wherein the control device determines the second holding position determining signal based on a plurality of holding position determining signals stored beforehand in accordance with the elapsed time after the start of friction stir welding. 
     
     
       7. The friction stir welding apparatus according to  claim 1 , wherein
 the friction stir welding apparatus includes a sensor that detects a state of the pressing force receiving portion, and 
 the control device corrects the first holding position determining signal in accordance with the state of the pressing force receiving portion detected by the sensor to determine the second holding position determining signal. 
 
     
     
       8. The friction stir welding apparatus according to  claim 1 , wherein the control device corrects the holding position of the holder unit by the second vertical movement drive mechanism unit in accordance with the determined second holding position determining signal when the second holding position determining signal is determined by correcting the first holding position determining signal in accordance with a state of the pressing force receiving portion. 
     
     
       9. A friction stir welding apparatus that joins joining target members by friction stir welding, the friction stir welding apparatus comprising:
 a control device that controls an operation of the friction stir welding apparatus; 
 a multi-axis robot arm that has multiple joints and is configured to freely move in a three-dimensional space; 
 a C-shaped frame holding unit connected to a tip of the multi-axis robot arm; 
 a C-shaped frame connected to the C-shaped frame holding unit via a first vertical movement drive mechanism unit; 
 a holder unit connected to one end of the C-shaped frame via a second vertical movement drive mechanism unit; and 
 a joining tool held by the holder unit, 
 wherein the C-shaped frame includes 
 a held portion connected to the C-shaped frame holding unit via the first vertical movement drive mechanism unit, 
 a holder unit holding portion connected to the holder unit via the second vertical movement drive mechanism unit, and 
 a pressing force receiving portion connected to the other end of the C-shaped frame and receiving a pressing force from the joining tool, 
 the control device includes 
 a first joining mode that performs friction stir welding based on a joining command signal that determines a joining condition of the joining tool, and a first holding position determining signal that determines a first holding position of the first vertical movement drive mechanism unit, and 
 a second joining mode that performs friction stir welding based on the joining command signal and a second holding position determining signal obtained by correcting the first holding position determining signal such that a depth or a range of a joined portion becomes constant in accordance with a state of the pressing force receiving portion, and 
 the first joining mode and the second joining mode are included in one joining pass from insertion of the joining tool into the joining target members to extraction of the joining target members. 
 
     
     
       10. The friction stir welding apparatus according to  claim 9 , wherein the control device determines the joining condition of the joining tool, and the holding position of the C-shaped frame by the first vertical movement drive mechanism unit in either the first joining mode and the second joining mode. 
     
     
       11. The friction stir welding apparatus according to  claim 10 , wherein the control device starts friction stir welding for the joining target members in the first joining mode, and switches to the second joining mode after an elapse of a predetermined time. 
     
     
       12. The friction stir welding apparatus according to  claim 9 , wherein
 the friction stir welding apparatus includes a sensor that detects a state of the pressing force receiving portion, and 
 the control device corrects the first holding position determining signal in accordance with the state of the pressing force receiving portion detected by the sensor to determine the second holding position determining signal.